Wingmen can be found in Bars. For a fee, they will travel with you for a set length of time (several hours) helping protect you from encounters with Pirates, Retros or Kilrathi. After the stipulated time has passed they will ask you if you'd like to repeat the deal, for the same price. If you decline they fly their own way.
You can communicate with them the normal way ('C' and 'Shift-C' keys) or per shortcut 'Shift-W' to tell them who to attack.